Imprint method, imprint apparatus, and article manufacturing method

ABSTRACT

An imprint apparatus forms a pattern of an imprint material on a substrate by using a mold. A substrate holding unit holds the substrate by a suction force between the substrate and a holding surface and includes a first suction unit for sucking a rear surface of a first region of the substrate with a first suction force and a second suction unit for sucking a rear surface of a second region of the substrate with a second suction force. A deformation mechanism deforms a shape of the first region in a direction along the holding surface when forming the pattern of the imprint material on the first region. An adjusting unit adjusts the first and second suction forces. The first suction force is less than the second in at least a portion of a period during the deforming of the shape of the first region by the deformation mechanism.

This application is a continuation of copending U.S. patent applicationSer. No. 14/887,472, filed Oct. 20, 2015, which is a continuation ofU.S. patent application Ser. No. 13/647,667, filed Oct. 9, 2012, whichmatured into U.S. Pat. No. 9,201,298.

This application also claims the benefit of Japanese Patent ApplicationNo. 2011-226636, filed Oct. 14, 2011, and Japanese Patent ApplicationNo. 2012-220209, filed Oct. 2, 2012, which are hereby incorporated byreference herein in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an imprint method, an imprintapparatus, and an article manufacturing method.

Description of the Related Art

As the demand for microfabrication of semiconductor devices or MEMSincreases, not only has conventional photolithography technology, butalso, microfabrication technology, in which an uncured resin on asubstrate is molded by a mold to thereby form a resin pattern on thesubstrate, has been receiving attention. This technology is alsoreferred to as “imprint technology”, by which a fine structure withdimensions of a few nanometers can be formed on a substrate. One exampleof the imprint technology includes a photo-curing method. An imprintapparatus employing the photo-curing method first applies an ultravioletcurable resin (imprint material, photocurable resin) to a shot (imprintregion) on a substrate (wafer). Next, the resin (uncured resin) ismolded by a mold. After the ultraviolet curable resin is irradiated withultraviolet light for curing, the cured resin is released from the mold,whereby a resin pattern is formed on the substrate.

Here, in a series of device manufacturing steps, heat processing in afilm formation step, such as sputtering, is performed for a substrate tobe subjected to imprint processing. Consequently, the entire substratemay be expanded or reduced, resulting in a change in the shape (size) ofthe pattern in the direction of two orthogonal in-plane axes. Thus, inan imprint apparatus, the shape of the substrate-side pattern formed ona substrate needs to be matched with the shape of the pattern sectionformed on a mold when the mold is pressed against the resin on thesubstrate. In a conventional exposure apparatus, such shape correction(magnification correction) can be ensured by changing the size of eachshot during exposure processing by changing the reduction magnificationof a projection optical system in accordance with the magnification ofthe substrate or by changing the scanning speed of a substrate stage.However, the imprint apparatus does not have a projection optical systemand the mold is brought into direct contact with the resin on thesubstrate, and thus, it is difficult to perform such correction. Hence,the imprint apparatus employs a shape correction mechanism(magnification correction mechanism) that physically deforms a mold byimparting an external force to the sides of the mold or by expanding themold by heating.

For example, assume a case wherein the imprint apparatus is applied to amanufacturing step of manufacturing a semiconductor device having ahalf-pitch of about 32 nm. At this time, according to ITRS(International Technology Roadmap for Semiconductors), the superpositionaccuracy is 6.4 nm. In order to accommodate this, shape correction alsoneeds to be performed with an accuracy of a few nm or less. On the otherhand, the mold (pattern section) used in the imprint apparatus may alsobe distorted by the following causes. For example, the pattern surfaceof a mold is directed upward when the mold is being prepared, whereasthe pattern surface thereof is directed downward when the mold is used(during pressing). Thus, the pattern section may be deformed upon usageunder the influence of gravity. Although the pattern section istypically formed by a drawing apparatus using an electron beam, or thelike, the pattern section may also be distorted due to distortionaberration of the optical system of the drawing apparatus duringformation thereof. Furthermore, even if the pattern section can beprepared without distortion, the occurrence of distortion in asubstrate-side pattern may result in an adverse effect on thesuperposition accuracy. Accordingly, in order to suppress suchdistortion (deformation) of the mold and to improve superpositionaccuracy, Japanese Patent Laid-Open No. 2004-259985 discloses a patternforming apparatus that controls the temperature of a mold and asubstrate by means of a retention temperature control unit, and correctsthe shape of the mold or the substrate by generating desired thermaldeformation in the mold or the substrate.

In the conventional imprint apparatus, however, a substrate is held by asubstrate holding unit, such as a wafer chuck, with the bottom surfaceof the substrate restricted thereto. Thus, even if thermal deformationis generated on the substrate under temperature control disclosed inJapanese Patent Laid-Open No. 2004-259985, it is still difficult tosufficiently change the shape of the substrate-side pattern relative tothe shape of the pattern section. Accordingly, an imprint apparatus isdesired that is capable of improving superposition accuracy between amold and a resin on a substrate by readily implementing not only thecorrection of the shape of the mold, but also, the correction of theshape of the substrate (including the substrate-side pattern) relativeto the shape of the mold.

SUMMARY OF THE INVENTION

The present invention provides an imprint apparatus that is advantageousfor improving superposition accuracy between a mold and resin on asubstrate.

According to one aspect, the present invention provides an imprintapparatus for forming a pattern of an imprint material on a substrate byusing a mold that includes a substrate holding unit configured to holdthe substrate by acting a suction force between the substrate and aholding surface, the substrate holding unit including a first suctionunit for sucking a rear surface of a first region of the substrate witha first suction force and a second suction unit for sucking a rearsurface of a second region of the substrate different from the firstregion of the substrate with a second suction force, a deformationmechanism configured to deform a shape of the first region in adirection along the holding surface when forming the pattern of theimprint material on the first region, and an adjusting unit configuredto adjust the first suction force and the second suction force. Theadjusting unit adjusts the first suction force to be less than thesecond force in at least a portion of a period during the deforming ofthe shape of the first region by the deformation mechanism.

According to another aspect, the present invention provides a method ofmanufacturing an article including the steps of (a) forming a pattern ofan imprint material on a substrate using an imprint apparatus forforming the pattern on the substrate by using a mold, (b) processing thesubstrate on which the pattern is formed by the forming, and (c)manufacturing the article from the processed substrate. The imprintapparatus includes (i) a substrate holding unit configured to hold thesubstrate by acting as a suction force between the substrate and aholding surface, the substrate holding unit including a first suctionunit for sucking a rear surface of a first region of the substrate witha first suction force and a second suction unit for sucking a rearsurface of a second region of the substrate different from the firstregion of the substrate with a second suction force, (ii) a deformationmechanism configured to deform a shape of the first region in adirection along the holding surface when forming the pattern of theimprint material on the first region, and (iii) an adjusting unitconfigured to adjust the first suction force and the second suctionforce. The adjusting unit adjusts the first suction force to be lessthan the second force in at least a portion of a period during thedeforming of the shape of the first region by the deformation mechanism.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the configuration of an imprintapparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating the configuration of a wafer stageaccording to the first embodiment.

FIG. 3 is a flowchart illustrating the sequence of operations accordingto the first embodiment.

FIG. 4A is a flowchart illustrating the sequence of operations accordingto a second embodiment.

FIG. 4B is a flowchart illustrating a variant example of the sequence ofoperations shown in FIG. 4A.

FIG. 5 is a diagram illustrating the configuration of a wafer stageaccording to a third embodiment.

FIG. 6 is a flowchart illustrating the sequence of operations accordingto a fourth embodiment.

FIG. 7 is a diagram illustrating the irradiation dose of light accordingto the fourth embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

First Embodiment

First, a description will be given of the configuration of an imprintapparatus according to a first embodiment of the present invention. FIG.1 is a schematic diagram illustrating the configuration of an imprintapparatus 1 of the present embodiment. The imprint apparatus 1 is anapparatus that molds an uncured resin on a wafer (on a substrate), i.e.,a substrate to be treated, using a mold, to thereby form a resin patternon the wafer, which is used in the manufacture of devices, such assemiconductor devices, and the like, as articles. Note that the imprintapparatus of the present embodiment is an apparatus employing aphoto-curing method. In the following drawings, a description will begiven in which the Z axis is aligned parallel to the optical axis of anirradiation system that irradiates a resin on a wafer with ultravioletlight, and mutually orthogonal axes, X and Y, are aligned in a planeperpendicular to the Z axis. The imprint apparatus 1 includes a lightirradiation unit 2, a mold holding mechanism 3, a wafer stage 4, anapplication unit 5, and a control unit 6.

The light irradiation unit 2 irradiates a mold 7 with ultraviolet light8 during imprint processing. The light irradiation unit 2 is constitutedby a light source 9 and an optical element 10 that adjusts theultraviolet light 8 emitted from the light source 9 to light suitablefor imprinting. Note that, in the present embodiment, the lightirradiation unit 2 is installed for employing a photo-curing method. If,however, a thermosetting method is employed, a heat source unit forcuring a thermosetting resin may be installed, instead of the lightirradiation unit 2. Furthermore, the light irradiation unit 2 includes aheating light source 50 that functions as a heating mechanism (substratedeformation mechanism) for heating a wafer 11 by irradiating the wafer11 with light in addition to light from the light source 9. The lightirradiated by the heating light source 50 is light near the wavelengthrange of infrared light, to which a photocurable resin is not sensitive.The heating mechanism also includes an adjuster that forms apredetermined irradiation dose distribution of light. In the presentembodiment, a description will be given on the assumption that theheating light source 50 is integrated with the adjuster. Note that theadjuster may be provided separately from the heating light source 50.For example, a liquid crystal device including a plurality of liquidcrystal elements arranged in a region irradiated with light emitted fromthe heating light source 50 or a mirror device, including a plurality ofmirrors arranged in a region irradiated with light, may also be used.Here, the mirror device may also be referred to as a “digital mirrordevice” or a “micro mirror device”. The liquid crystal device is capableof forming a predetermined irradiation dose distribution byindependently adjusting voltages to be applied to a plurality of liquidcrystal elements, whereas the mirror device is capable of forming apredetermined irradiation dose distribution by independently adjustingthe surface directions of a plurality of mirrors.

The outer peripheral shape of the mold 7 is rectangular, and the mold 7includes a pattern section (e.g., a circuit pattern, or the like) 71, inwhich the concave and convex pattern is three-dimensionally formed onthe surface of the facing wafer 11. Also, the material of the mold 7 isa material such as quartz, or the like, through which the ultravioletlight 8 can pass. Furthermore, the mold 7 may be of a shape in which acavity (concave portion) 7 b for facilitating the deformation of themold 7 is formed on the surface onto which the ultraviolet light 8 isirradiated. The cavity 7 b has a circular planar shape, and thethickness (depth) of the cavity 7 b is appropriately set, depending onthe size or the material of the mold 7. A light transmission member 13may also be installed within an aperture region 17 in the mold holdingmechanism 3, to be described below, such that a space 12 enclosed by apart of the aperture region 17 and the cavity 7 b is sealed, and thepressure in the space 12 may be adjusted by a pressure adjusting device(not shown). For example, the pressure adjusting device sets thepressure in the space 12 to be higher than the external pressure whenthe mold 17 is pressed against a resin 14 on the wafer 11, so that thepattern section 7 a is deflected into a convex shape toward the wafer11, and the pattern section 7 a is brought into contact with the resin14 from the central portion of the pattern section 7 a. With thisarrangement, gas (air) is prevented from being entrapped between thepattern section 7 a and the resin 14, so that the resin 14 can be filledin every corner of the convex and concave portion of the pattern section7 a.

The mold holding mechanism 3 has a mold chuck 15 that holds the mold 7by suctioning/attracting the mold 7 using a vacuum suction force/and anelectrostatic attraction force, and a mold drive mechanism 16 that holdsthe mold chuck 15 and moves the mold 7 (the mold chuck 15). Also, eachof the mold chuck 15 and the mold drive mechanism 16 has the apertureregion 17 at the central portion (the inside thereof), such that theultraviolet light 8, emitted from the light source 9 of the lightirradiation unit 2, is irradiated toward the wafer 11. Furthermore, themold holding mechanism 3 has a magnification correction mechanism (molddeformation mechanism) 18 that corrects the shape of the mold 7 (thepattern section 7 a) by imparting an external force or a displacement tothe side surface of the mold 7. The magnification correction mechanism18 is installed at the mold 7 holding side of the mold chuck 15. Themagnification correction mechanism 18 deforms the shape of the mold 7,to thereby match the shape of the pattern section 7 a formed on the mold7 relative to the shape of the area on the substrate (substrate-sidepattern area) 53 where the pre-existing pattern is formed. If it isdifficult to match the shape of the pattern section 7 a relative to theshape of the substrate-side pattern area 53, the magnificationcorrection mechanism 18 may also be adapted to make the shapes of bothpatterns close to each other (i.e., to reduce a shape differentialbetween the two). While the one substrate-side pattern area 53 is shownin the figure, a plurality of substrate-side pattern areas are formed onthe wafer 11.

The mold drive mechanism 16 moves the mold 7 in the Z-axis direction soas to relatively bring the mold 7 into contact with the resin 14 on thewafer 11, or to release the mold 7 from the resin 14. Examples of anactuator employable for the mold drive mechanism 16 include a linearmotor, an air cylinder, and the like. Also, the mold drive mechanism 16may be constituted by a plurality of drive systems, such as a coarsemovement drive system, a fine movement drive system, and the like, inorder to accommodate position of the mold 7 with high accuracy.Furthermore, the mold drive mechanism 16 may have a position adjustmentfunction for adjusting the position of the mold 7, not only in theZ-axis direction, but also, in the X-axis direction, the Y-axisdirection, or the θ (rotation about the Z axis) direction, a tiltfunction for correcting the tilt of the mold 7, and the like. Thecontacting operation and the releasing operation performed by theimprint apparatus 1 may be realized by moving the mold 7 in the Z-axisdirection, may be realized by moving the wafer stage 4 in the Z-axisdirection, or may also be realized by moving both the mold 7 and thewafer stage 4 relative to each other.

The wafer 11 is, for example, a single crystal silicon substrate or anSOI (Silicon on Insulator) substrate, and an ultraviolet curable resin(hereafter referred to as “resin”) 14, which is molded by the patternsection 7 a formed in the mold 7, is applied on the treatment surface ofthe wafer 11.

The wafer stage 4 holds the wafer 11 and executes position matchingbetween the mold 7 and the resin 14 before, or while the mold 7 isbrought into contact with the resin 14 on the wafer 11. The wafer stage4 has a wafer chuck (substrate holding unit) 19, on which a holdingsurface for holding the wafer 11 is formed, and a stage drive mechanism20 that holds the wafer chuck 19 by a mechanical unit and is movable inthe XY plane.

FIG. 2 is a schematic cross-sectional diagram illustrating the waferchuck 19 of the present embodiment and the configuration of theperipheral portion thereof. The wafer chuck 19 includes a plurality ofsuction units 51 that holds the rear surface of the wafer 11 by suction.As shown in FIG. 2, the suction units 51 may be constituted by, forexample, three suction units 51 a to 51 c. These suction units 51 a to51 c are connected to a pressure adjusting device 52 separate from theaforementioned pressure adjusting device, and function as a frictionalforce adjusting mechanism that adjusts the frictional force actingbetween the rear surface of the wafer 11 corresponding to a regionincluding the substrate-side pattern area 53 and the surface of thewafer chuck 19. The pressure adjusting device 52 adjusts the pressure toreduce the pressure between the wafer 11 and the suction units 51, tothereby generate a suction force. Consequently, the pressure adjustingdevice 52 is capable of independently changing pressure values (suctionforces) applied by the suction units 51 a to 51 c, while holding thewafer 11 on the surface of the wafer chuck 19. Note that the number ofdivided suction units 51 is not limited to three, but may be any number.Also, the wafer chuck 19 has a reference mark 21 that is used when themold 7 is subjected to alignment on the surface thereof.

Examples of an actuator employable for the stage drive mechanism 20include a linear motor. The stage drive mechanism 20 may also beconstituted by a plurality of drive systems, such as a coarse movementdrive system, a fine movement drive system, and the like, with respectto the X-axis and Y-axis directions. Furthermore, the stage drivemechanism 20 may have a drive system for adjusting the position of thewafer 11 in the Z-axis direction, a position adjustment function foradjusting the position of the wafer 11 in the 0 direction, a tiltfunction for correcting the tile of the wafer 11, and the like.

The application unit 5 applies the resin (uncured resin) 14 to the wafer11. Here, the resin 14 is a photocurable resin (imprint material) havingthe property of being cured by receiving irradiation of the ultravioletlight 8, and is appropriately selected depending on various conditions,such as the manufacturing process of semiconductor devices, or the like.The amount of the resin 14 to be ejected from the ejection nozzle of theapplication unit 5 is also appropriately determined by a desiredthickness of the resin 14 to be formed on the wafer 11, the density ofthe pattern to be formed, or the like.

The control unit 6 may control the operation, adjustment, and the like,of the components of the imprint apparatus 1. The control unit 6 isconstituted by a computer, or the like, and is connected to thecomponents of the imprint apparatus 1 through a line so as to executecontrol of the components by a program, or the like. The control unit 6of the present embodiment may control the operation of at least thelight irradiation unit 2, the wafer stage 4, and the pressure adjustingdevice 52. Note that the control unit 6 may be integrated with the restof the imprint apparatus 1 (provided in a common housing) or may beprovided separately from the rest of the imprint apparatus 1 (providedin a separate housing).

Also, the imprint apparatus 1 includes an alignment measurement system22 that measures a positional shift between an alignment mark formed onthe wafer 11 and an alignment mark formed on the mold 7 in eachdirection of the X-axis and the Y-axis as wafer alignment. Furthermore,the imprint apparatus 1 includes a base surface plate 24, on which thewafer stage 4 is placed, a bridge surface plate 25 that fixes the moldholding mechanism 3, and a strut 26 that is extended from the basesurface plate 24, and supports the bridge surface plate 25. Furthermore,the imprint apparatus 1 includes a mold conveyance mechanism (not shown)that conveys the mold 7 from the exterior of the apparatus to the moldholding mechanism 3 and a substrate conveyance mechanism (not shown)that conveys the wafer 11 from the exterior of the apparatus to thewafer stage 4.

Next, a description will be given of imprint processing performed by theimprint apparatus 1. First, the control unit 6 places the wafer 11 onthe wafer chuck 19 of the wafer stage 4 using the substrate conveyancemechanism, holds the wafer 11 on the holding surface of the wafer chuck19 (holding step), and then moves the wafer stage 4 to the applicationposition of the application unit 5. Then, as an application step, theapplication unit 5 applies the resin 14 to the substrate-side patternarea (a shot area) 53. Next, the control unit 6 moves the wafer stage 4such that the substrate-side pattern area 53 on the wafer 11 is placedin a position directly below the pattern section 7 a formed in the mold7. Next, the control unit 6 drives the mold drive mechanism 16 so as topress the mold 7 against the resin 14 on the wafer 11 (mold-pressingstep) so that the mold 7 is brought into contact with the resin 14(contacting step). During the contacting step, the resin 14 is filled inthe convex and the concave pattern of the pattern section 7 a. Underthis condition, as a curing step, the light irradiation unit 2 emits theultraviolet light 8 from the rear surface (the top surface) of the mold7, and cures the resin 14 by the ultraviolet light 8 that has beentransmitted through the mold 7. Then, after the resin 14 is cured, thecontrol unit 6 drives the mold drive mechanism 16 again, to therebyrelease the mold 7 from the resin 14 (mold-releasing step). By theaforementioned steps, a three-dimensionally shaped pattern (layer) ofthe resin 14 following the convex and concave pattern of the patternsection 7 a is formed on the surface of the substrate-side pattern area53 on the wafer 11. Such a sequence of imprint operations is conductedtwo or more times, while the substrate-side pattern area 53 is changedunder the drive of the wafer stage 4, to thereby be able to form aplurality of patterns of the resin 14 on one wafer 11.

Here, a description will be given of the suction control by means of thewafer chuck 19 when a pattern is formed on the wafer 11 for apredetermined shot. FIG. 3 is a flowchart illustrating the sequence ofoperations from the mold-processing step to the curing step performed bythe imprint apparatus 1. At this time, a shot to be processed is locatedat the central portion of the wafer 11, and, as shown in FIG. 2, theposition is intended to correspond to the suction unit 51 b provided inthe wafer chuck 19. In this case, the control unit 6 causes the pressureadjusting device 52 to reduce only the suction force generated by thesuction unit 51 b, while maintaining the suction force generated by thesuction units 51 a and 51 c prior to the correction of the shape of thepattern section 7 a and the wafer 11 (step S 100). For example, thesuction pressure of the suction unit 51 b may be ambient pressure. Ifthe suction pressure of the suction unit 51 b is less than the suctionforce generated by the suction units 51 a and 51 c, the suction pressureof the suction unit 51 b may be ambient pressure or less. When theadjusting range of the irradiation dose of light emitted from theheating light source 50 is set in advance, the suction pressure of thesuction unit 51 b may be set such that the thermal deformation force Wacting o the substrate-side pattern area 53 in a direction along thesurface of the wafer 11 is greater than the maximum static frictionalforce F acting between the rear surface of the wafer 11 and the suctionunit 51 b. When the temperature rise of the substrate-side pattern area53 is give as “ΔT”, the thermal expansion coefficient thereof is givenas “α”, and the modulus of elasticity thereof is given as “E”, all ofwhich are determined depending on the irradiation dose, the thermalstress “σ” can be approximately expressed as the products of α, E, andΔT. The thermal deformation force W, depending on the thermal stress “a”and the cross-sectional area “S”, acts on the substrate-side patternarea 53. When the maximum static frictional coefficient is given as “p.”and the vertical direction depending on the suction pressure is given as“N”, the maximum static frictional force F can be expressed as theproduct of μ and N. In other words, it is only necessary to satisfy therelationship of F<W. Note that the region on the wafer 11 held by thesuction unit 51 b may be a region including at least the substrate-sidepattern area 53 where the pattern is pre-formed on the wafer 11. Next,the control unit 6 causes the alignment measurement system 22 to measurethe positions of the mold 7 and the wafer 11 in the X-axis and theY-axis directions (first alignment measurement, step S101), and acquiresinformation regarding differences between the shape of the patternsection 7 a and the shape of the substrate-side pattern area 53(acquiring step). However, when it is desired to correct only the shapeof the substrate-side pattern area 53 formed on the wafer 11, thecontrol unit 6 may acquire only information regarding the shape of thesubstrate-side pattern area 53. Then, the control unit 6 calculates thecorrection amount to a positional shift between the pattern section 7 aand the substrate-side pattern area 53 based on the measurement resultobtained in step S101. Next, the control unit 6 causes the heating lightsource 50 of the light irradiation unit 2 to heat the wafer 11 byirradiating the wafer 11 with light (deformation step: step S102), andcauses the magnification correction mechanism 18 to operate forinputting displacement (mold-deformation step: step S103), and thus, theshapes of the pattern section 7 a and the substrate side pattern area 53are corrected. Since the maximum static frictional force acting betweenthe rear surface of the wafer 11 corresponding to the substrate-sidepattern area 53 and the holding surface is reduced, as described above,the thermal deformation force greater than the maximum static frictionalforce F can be applied to the wafer 11 in a direction along the surfacethereof. Also, a temperature distribution is imparted to thesubstrate-side pattern area 53 by irradiating the substrate-side patternarea 53 with light having an irradiation dose distribution, whereby theshape of various components can be corrected. For example, among thecalculated correction amount, a low-order component (e.g., a trapezoidalcomponent) is corrected by heating the wafer 11 and a high-ordercomponent is corrected by displacement input, whereby the shape of thepattern section 7 a can be preferably matched with the shape of thesubstrate-side pattern area 53. When the shape of the pattern section 7a is matched with the shape of the substrate-side pattern area 53, as aresult of correction, the control unit 6 causes the pressure adjustingdevice 52 to reduce the suction pressure of the suction unit 51 b again,so as to return the suction force generated by the suction unit 51 bback to the level of the suction force generated by the suction units 51a and 51 c (step S104). Next, the control unit 6 causes the alignmentmeasurement system 22 to measure the positions of the mold 7 and thewafer 11, again, in the X-axis and the Y-axis directions (secondalignment measurement: step S105). Here, if it is determined that apositional shift is present between the mold 7 and the wafer 11, thecontrol unit 6 causes the mold drive mechanism 16 or the stage drivemechanism 20 to drive, to perform position adjustment between the mold 7and the wafer 11 (step S106). Then, the control unit 6 proceeds to thenext process in the curing step.

The step of reducing the suction force generated by the suction unit 51b in step S100 may be started, not only prior to the first alignmentmeasurement in step S101, but also, after the first alignmentmeasurement. It is preferable that the step of reducing the suctionforce generated by the suction unit 51 b is performed prior to or duringthe deforming step of heating a substrate. In step S102, the correctionof the shape of the substrate-side pattern area 53 on the wafer 11 isperformed by heating due to the irradiation of light from the heatinglight source 50, but the present invention is not limited thereto. Forexample, in a substrate deformation mechanism, instead of the heatinglight source 50, a separately provided external force applying mechanismmay impart an external force or input displacement in a planar directiondirectly to the wafer 11, to thereby perform the correction of the shapeof the substrate-side pattern area 53. Furthermore, the shape of thesubstrate-side pattern area 53 may be matched with the shape of thepattern section 7 a by performing shape correction only due to theheating of the wafer 11 in step S102, without performing thedisplacement input to the mold 7 in step S103. Note that steps S102 andstep S103 may be performed inversely or in parallel. Also, it ispreferable that the step of recovering the suction force generated bythe suction unit 5 lb is performed after the deforming step, and priorto the mold-releasing step.

As described above, in the imprint apparatus 1, the suction forcegenerated by the suction unit 5 lb is reduced during a period from themold-pressing step to the curing step, to thereby reduce a frictionalforce between the suction unit 51 b and the rear surface of the wafer11, including at least the substrate-side pattern area 53. Specifically,during the thermal deformation of the substrate-side pattern area 53 bythe heating light source 50 of the light irradiation unit 2, africtional force acting between the wafer chuck 19 and the rear surfaceof the wafer 11, corresponding to the substrate-side pattern area 53, isreduced more than when the substrate-side pattern area 53 is notsubjected to thermal deformation. Thus, the substrate-side pattern area53 can be efficiently deformed by heating. In other words, thesubstrate-side pattern area 53 can be deformed by heating without anunnecessary increase in irradiation dose, and thus, an unnecessary risein temperature of the peripheral members can be suppressed.Consequently, the adverse effect on superposition accuracy between themold 7, and the resin 14 on the wafer 11, can be suppressed.Furthermore, at this time, the suction force generated by other suctionunits 51 a and 51 c remains maintained. Consequently, the wafer 11 isfirmly fixed on the wafer chuck 19 by suction, even if the wafer 11 issubjected to thermal deformation, and thus, displacement of the entirewafer 11 is suppressed. There is no need to reduce a frictional force atall times during thermal deformation, but a frictional force may bereduced in at least a portion of the period during thermal deformation.

As described above, according to the present embodiment, the imprintapparatus 1, which is advantageous for improving superposition accuracybetween the mold 7 and the resin 14 on the wafer 11, may be provided.

Second Embodiment

Next, a description will be given of an imprint apparatus according to asecond embodiment of the present invention. The imprint apparatus of thepresent embodiment has the same configuration as that of the firstembodiment, but the sequence of operations from the mold-pressing stepto the curing step is changed. FIGS. 4A and 4B are flowchartsillustrating the sequence of operations from the mold-pressing step tothe curing step performed by the imprint apparatus 1 according to thepresent embodiment. First, in the example shown in FIG. 4A, after themold-pressing step, the control unit 6 causes the magnificationcorrection mechanism 18 to perform the displacement input to the mold 7in step S 103, in the sequence of operations of the first embodimentshown in FIG. 3, after the second alignment measurement in step S105(step S205). Here, given that the alignment measurement in step S201 isthe first alignment measurement, a step corresponding to a step S105,shown in FIG. 3, is the second alignment measurement shown in FIG. 4A(step S204). In this case, the control unit 6 causes the alignmentmeasurement system 22 to perform the third alignment measurement thesame as the second alignment measurement, again, after step S205 (stepS206). Note that the third alignment measurement may be omitted by usingthe value obtained by the second alignment measurement. The processes inother steps are the same as those in the first embodiment.

On the other hand, in the example shown in FIG. 4B, after themold-pressing step, the control unit 6 causes the magnificationcorrection mechanism 18 to perform the displacement input to the mold 7in step S103 in the sequence of operations of the first embodiment shownin FIG. 3, prior to the process of reducing the suction force generatedby the suction unit 51 b in step S100 (step S301). In this case, thecontrol unit 6 causes the alignment measurement system 22 to perform thefirst alignment measurement, which is a process corresponding to stepS101 shown in FIG. 3, prior to step S301 (step S300). Also, the controlunit 6 starts the process of reducing the suction force generated by thesuction unit 51 b, which corresponds to step S100 shown in FIG. 3, afterstep S301 (step S302). Then, after step S304, corresponding to step S102shown in FIG. 3, which is the correction of the shape of thesubstrate-side pattern area 53 on the wafer 11, the control unit 6raises the suction force generated by the suction unit 51 b again (stepS305). The processes in the other steps are the same as those in thefirst embodiment. According to the present embodiment, as shown in FIGS.4A and 4B, the displacement input to the mold 7 by means of themagnification correction mechanism 18 is not performed while africtional force is being reduced. Thus, the same effects as those inthe first embodiment may be provided. In addition, unnecessarypositional shift or unnecessary deformation of the wafer 11, inassociation with deformation of the mold 7 upon inputting ofdisplacement, can be further suppressed.

Third Embodiment

Next, a description will be given of an input apparatus according to athird embodiment of the present invention. In the imprint apparatus ofthe present embodiment, the configuration of the suction units 51provided in the wafer chuck 19 according to the first embodiment ischanged. FIG. 5 is a schematic cross-sectional diagram illustrating anenlarged portion of the suction unit 51 (51 a) provided in the waferchuck 19 according to the present embodiment. The suction unit 51 has aplurality of suction pins 60 within the suction region, and alow-friction member 61 made of a low-friction material having a lowfriction coefficient against the wafer 11 is provided at the tip surfaceof each suction pin 60, i.e., the surface in contact with the rearsurface of the wafer 11. Examples of such a low-friction materialinclude DLC (diamond-like carbon). As described above, a frictionalcoefficient of the contact surface between the wafer chuck 19 and thewafer 11 is reduced, and thus, the wafer 11 (the substrate-side patternarea 53) can be efficiently deformed by heating with the heating lightsource 50 of the light irradiation unit 2.

Fourth Embodiment

Next, a description will be given of an imprint apparatus according to afourth embodiment of the present invention. In the imprint apparatus ofthe first embodiment, a description has been given by taking an examplein which a frictional force, acting between the rear surface of thewafer 11 corresponding to the substrate-side pattern area 53 and theholding surface of the wafer chuck 19, is adjusted. In the presentembodiment, a description will be given taking an example in which athermal deformation force acting on the substrate-side pattern area 53is adjusted, without adjusting the friction force. Since theconfiguration of the imprint apparatus of the present embodiment is thesame as that of the first embodiment, except that the control unit 6 isdifferent in terms of function, a description of the configurationthereof will be omitted, while focusing on the function of the controlunit 6.

FIG. 6 is a flowchart illustrating the sequence of operations from themold-pressing step to the curing step performed by the imprint apparatus1 of the present embodiment. First, the control unit 6 reads the valueof the suction pressure of the suction unit 51 b provided in the waferchuck 19 after the mold-pressing step (step S400). Next, the controlunit 6 orders to perform first alignment measurement corresponding tothe process in step S101 shown in FIG. 3 (step S401). The control unit 6calculates the irradiation dose of light irradiated on a wafer, based onthe value of the suction pressure of the suction unit 51 b obtained instep S400 (step S402). Next, the shape of the substrate-side patternarea 543 is corrected by irradiating the wafer 11 with the calculatedirradiation dose of light (step S403). Then, the displacement input tothe mold 7 (step S404 corresponding to step S103 shown in FIG. 3) andthe second alignment measurement (step S405 corresponding to step S105shown in FIG. 3) are executed. When a positional shift is presentbetween the mold 7 and the wafer 11, position adjustment between themold 7 and the wafer 11 (step S406) is performed. Then, the curing stepis performed.

A description will be given of an irradiation dose to be calculated instep S402, with reference to FIG. 7. The heating mechanism irradiatesthe irradiation region on the wafer 11, including at least thesubstrate-side pattern area 53 with light obtained as the sum of auniform irradiation dose a and an irradiation dose b having adistribution. Here, the irradiation dose a is a uniform irradiation dosewith respect to an irradiation region, in which a thermal deformationforce applied to the irradiation region on the wafer 11 in a directionalong the plane thereof is greater than the maximum static frictionalforce acting between the rear surface of the irradiation region on thewafer 11 and the suction unit 51. The irradiation dose b is anirradiation dose having a distribution with respect to an irradiationregion depending on the correction amount of the substrate-side patternarea 53 calculated by the control unit 6, or depending on the valueobtained by subtracting the amount of deformation of the wafer 11 causedby the irradiation dose α from the correction amount.

It is preferable that the irradiation dose α is determined depending onthe suction pressure of the suction unit 51 b (suction force). When thetemperature rise of the substrate-side pattern area 53 is given as “ΔT”,the thermal expansion coefficient thereof is given as “α”, and themodulus of elasticity thereof is given as “E”, all of which aredetermined depending on the irradiation dose. The thermal stress “σ” canbe approximately expressed as the product of σ, E, and ΔT. The thermaldeformation force W depending on the thermal stress “σ” and thecross-sectional area “S” acts on the substrate-side pattern area 53.When the maximum static frictional coefficient is given as “μ” and thevertical directional force depending on the suction pressure is given as“N”, the maximum static frictional force F can be expressed as theproduct of μ and N. In other words, it is only necessary to satisfy therelationship F<W. It is preferable that the irradiation dose b isdetermined on the basis of irradiation dose data prepared in advance,corresponding to the correction amount or the relationship in which thecorrection amount is associated with the irradiation dose.

In the present embodiment, although the suction pressure of the suctionunit 51 is not adjusted for reducing a frictional force, the wafer 11 isheated by the irradiation of light at the irradiation dose α, such thatthermal deformation force does not exceed the maximum static frictionalforce. Consequently, the shape of the substrate-side pattern area 53 canbe efficiently corrected, as in the first embodiment. The presentembodiment can be combined with pressure adjustment in the firstembodiment.

(Article Manufacturing Method)

A method of manufacturing a device (e.g., a semiconductor integratedcircuit element, a liquid display element, or the like), as an article,may include a step of forming a pattern on a substrate (e.g., a wafer, aglass plate, a film-like substrate, or the like) using the imprintapparatus described above. Furthermore, the manufacturing method mayinclude a step of etching the substrate on which a pattern has beenformed. When other articles, such as a patterned medium (storagemedium), an optical element, or the like, is manufactured, themanufacturing method may include other steps of processing the substrateon which a pattern has been formed, instead of the etching step. Thearticle manufacturing method of the present embodiment has an advantage,as compared with a conventional article manufacturing method, in atleast one of performance, quality, productivity, and production cost ofan article.

While the embodiments of the present invention have been described withreference to exemplary embodiments, it is to be understood that theinvention is not limited to the disclosed exemplary embodiments. Thescope of the following claims is to be accorded the broadestinterpretation, so as to encompass all such modifications and equivalentstructures and functions.

We claim:
 1. An imprint apparatus for forming a pattern of an imprintmaterial on a substrate by using a mold, the imprint apparatuscomprising; a substrate holding unit configured to hold the substrate byacting a suction force between the substrate and a holding surface, thesubstrate holding unit including a first suction unit for sucking a rearsurface of a first region of the substrate with a first suction forceand a second suction unit for sucking a rear surface of a second regionof the substrate, different from the first region of the substrate, witha second suction force; a deformation mechanism configured to deform ashape of the first region in a direction along the holding surface whenforming the pattern of the imprint material on the first region; and anadjusting unit configured to adjust the first suction force and thesecond suction force, wherein the adjusting unit adjusts the firstsuction force to be less than the second force in at least a portion ofa period during the deforming of the shape of the first region by thedeformation mechanism.
 2. The imprint apparatus according to claim 1,wherein the adjusting unit adjusts the first suction force to be lessthan the second force in at least the portion of the period bydecreasing the first suction force to be less than a suction forcebetween the substrate and the holding surface when forming the patternof the imprint material on a region of the substrate different from thefirst region.
 3. The imprint apparatus according to claim 2, wherein,after the deforming of the shape of the first region into apredetermined shape by the deformation mechanism and prior to areleasing of the mold from the imprint material on the first region, theadjusting unit increases the first suction force.
 4. The imprintapparatus according to claim 1, further comprising an acquiring unitconfigured to acquire the shape of the first region by detecting aplurality of marks provided on the substrate, wherein the deformationmechanism deforms the shape of the first region so as to reduce adifference between a shape of a pattern formed on the mold and the shapeof the first region.
 5. The imprint apparatus according to claim 1,wherein the deformation mechanism includes a heating mechanismconfigured to heat the first region.
 6. The imprint apparatus accordingto claim 5, wherein the deformation mechanism heats the first region byirradiating light to the first region.
 7. The imprint apparatusaccording to claim 6, wherein the deformation mechanism causes an uneventemperature distribution in the first region by the irradiating light.8. The imprint apparatus according to claim 4, further comprising a molddeformation mechanism configured to deform a shape of the mold, whereinthe mold deformation mechanism deforms the shape of the mold and thedeformation mechanism deforms the shape of the first region so as toreduce the difference.
 9. The imprint apparatus according to claim 1,wherein, in at least the portion of the period, the adjusting unitdecreases a friction force between the first suction unit and thesubstrate to be less than a friction force between the second suctionunit and the substrate.
 10. The imprint apparatus according to claim 1,wherein, in at least the portion of the period, a force to deform thefirst region by the deformation mechanism is greater than a maximumstatic friction force acting between the first suction force and therear surface of the substrate.
 11. A method of manufacturing an article,the method comprising steps of: (a) forming a pattern of an imprintmaterial on a substrate using an imprint apparatus for forming thepattern on the substrate by using a mold; (b) processing the substrateon which the pattern is formed by the forming; and (c) manufacturing thearticle from the processed substrate, wherein the imprint apparatusincludes: (i) a substrate holding unit configured to hold the substrateby acting as a suction force between the substrate and a holdingsurface, the substrate holding unit including a first suction unit forsucking a rear surface of a first region of the substrate with a firstsuction force and a second suction unit for sucking a rear surface of asecond region of the substrate, different from the first region of thesubstrate, with a second suction force; (ii) a deformation mechanismconfigured to deform a shape of the first region in a direction alongthe holding surface when forming the pattern of the imprint material onthe first region, and (iii) an adjusting unit configured to adjust thefirst suction force and the second suction force, wherein the adjustingunit adjusts the first suction force to be less than the second force inat least a portion of a period during the deforming of the shape of thefirst region by the deformation mechanism.
 12. A method of manufacturingan article according to claim 11, further comprising adjusting, by theadjusting unit, the first suction force to be less than the second forcein at least the portion of the period by decreasing the first suctionforce to be less than a suction force between the substrate and theholding surface when forming the pattern of the imprint material on aregion of the substrate different from the first region.
 13. A method ofmanufacturing an article according to claim 12, wherein, after thedeforming of the shape of the first region into a predetermined shape bythe deformation mechanism and prior to a releasing of the mold from theimprint material on the first region, and further comprising adjustingthe first suction force by the adjusting unit.
 14. A method ofmanufacturing an article according to claim 11, further comprisingacquiring, by an acquiring unit, the shape of the first region bydetecting a plurality of marks provided on the substrate, wherein thedeformation mechanism deforms the shape of the first region so as toreduce a difference between a shape of a pattern formed on the mold andthe shape of the first region.
 15. A method of manufacturing an articleaccording to claim 11, wherein the deformation mechanism includes aheating mechanism and further comprising heating the first region by theheating mechanism.
 16. A method of manufacturing an article according toclaim 15, wherein the deformation mechanism heats the first region byirradiating light to the first region.
 17. A method of manufacturing anarticle according to claim 16, wherein the deformation mechanism causesan uneven temperature distribution in the first region by theirradiating light.
 18. A method of manufacturing an article according toclaim 14, further comprising deforming a shape of the mold, by a molddeformation mechanism, wherein the mold deformation mechanism deformsthe shape of the mold and the deformation mechanism deforms the shape ofthe first region so as to reduce the difference.
 19. A method ofmanufacturing an article according to claim 11, wherein, in at least theportion of the period, and further comprising adjusting, by theadjusting unit, a friction force between the first suction unit and thesubstrate to be less than a friction force between the second suctionunit and the substrate.
 20. A method of manufacturing an articleaccording to claim 11, wherein, in at least the portion of the period, aforce to deform the first region by the deformation mechanism is greaterthan a maximum static friction force acting between the first suctionforce and the rear surface of the substrate.